Changes in the potential and vibrational energies upon the formation of vacancies in oxygen-doped cores of crystallite-conjugation regions of polycrystalline 4d and 5d BCC transition metals

The changes in the potential (ucmpl) and vibrational (ɛcmpl) energies and the signs of changes in the interatomic spacings (Δacmpl) upon the formation of vacancies in oxygen-alloyed (OA) cores of crystallite-conjugation regions (CCR) in polycrystalline 4d and 5d transition metals Mo, Ta, and W have been determined. The potential energy upon the formation of vacancies (upon the formation of vacancy complexes with oxygen atoms—vacO complexes) in the OA cores of CCRs in polycrystalline Mo, Ta, and W increases (ucmpl are positive), as upon the formation of vacancies in pure CCR cores of transition bcc d metals. The vibrational energy upon the formation of vacancies in OA CCR cores in polycrystalline Mo, Ta, and W decreases (ɛvacO are negative). The negative sign of changes in the vibrational energy upon the formation of vacancies in the OA CCR cores in Mo, Ta, and W (ɛvacO < 0) agrees with the independent determinations of the sign of changes in the vibrational energy in the OA CCR cores in polycrystalline tungsten (ɛvacO)W using Mossbauer measurements of the Debye temperature. The signs of changes in the interatomic spacings upon the formation of vacancies in the OA CCR cores in polycrystals of Mo, Ta and W are negative (ΔaVacO < 0), in contrast to positive (0 < ΔaBCC) changes in the interatomic distances in the nearest neighborhood of vacancies formed in pure CCR cores in Mo, Ta, and W.